Automatic starting mechanism



Jan. 18, 1938. MAURER 2,105,947

AUTOMATIC STARTING MECHANISM Original Filed Aug. 7, 1933 2 Sheets-Sheet1 INVENTOR 4 0M!) 1%. mad/"er A TTORNE Y Jan. 18, 1938. p HMAURER2,105,947

AUTOMATIC STARTING MECHANISM I ori inal Filed Aug. "r, 1953 2Sheets-Sheet 2 speed 2.4 m.

witness A TTORNE Y Patented Jan. 18, 1938 UNITED STATES PATENT OFFiCEAUTOMATIC STARTING MECHANISM Application August 7,

1933, Serial No. 684,007

Renewed October 7, 1936 7 Claims.

This invention relates to automatic starting mechanism for internalcombustion engines and more particularly to devices for controlling theoperation of starting mechanism in accordance with the operatingcondition of the engine to be started.

It is an object of the present invention to provide a novel startercontrol which is simple and economical in construction and efficient and11(3) reliable in operation.

It is another object to provide such a device which insures accurate anddependable control of the starting operation It is a further object toprovide such a de- 1:, vice having a liberal range of adjustment forvarying its controlling functions.

It is another object to provide such a device, the controllingcharacteristics of which are substantially unaffected by variations inexternal operating conditions and in the operating conditions of theassociated components of the power plant.

Further objects and advantages will be apparent from the followingdescription taken in connection with the accompanying drawings inwhich:-

Fig. 1 shows semi-diagrammatically a preferred embodiment of theinvention in conjunction with a conventional type of internal combustionengine, the clutch pedal of which is used to control the initiation ofthe starting operaion;

Fig. 2 is a similar view of a second embodiment of the invention inwhich the accelerator pedal of the engine is utilized as a controlelement;

Fig. 3 is a similar view of a third embodiment of the invention in whichcertain of the controlling functions are performed in response to theintake vacuum of the engine; and

Fig. 4 is a diagram showing graphically the results secured by separatefield excitation as compared with the normal generator output.

Referring first to Fig. 1 of the drawings, there is illustrated aninternal combustion engine indicated generally by numeral 4, andprovided with a manually operable member 2 in the form of a clutch pedalof conventional type for controlling the transmission of powertherefrom. A starting system for the engine is illustrated comprising abattery 3, grounded at 4, connected by a lead 5 to a magnetic startingswitch 6 which in turn is connected by a lead 1 to a starting motor SMwhich is grounded at 8 to complete the starting circuit.

A control circuit for the magnetic starting switch 6 is providedcomprising the battery 3, lead .9, manual switch .1 l, which ispreferably the ignition switch of the engine, lead I2, solenoid E3 ofthe magnetic starting switch, and lead M which is grounded through thearmature of an engine-driven generator G to complete the controlcircuit. The generator G is employed to charge the battery 3 in theusual manner, the necessary connections being not illustrated since theyform no part of the present invention. It will be understood that theconnection of the control circuit to the generator G is in such adirection, that the generator opposes the flow of battery currentthrough the control circuit and thereby deenergizes the solenoid l3 whensufficient voltage has been built up in the generator.

According to the present invention, a field winding [5 of the generatorG is connected by a lead Hi to the lead l2adjacent the ignition switchH. It will thus be seen that the field winding I5 is immediatelyenergized by the full voltage of the battery 3 upon closure of theignition switch H.

A resistance element I1 is inserted in the lead l2 to the solenoid l3and is designed to reduce the current flowing through the lead I2 to amere holding value for said solenoid. In order to effect closure of thestarting switch 6, a make and break device l8 of any suitable type isbridged around the resistance I! and is operated by the clutch pedal 2to close the bridging circuit when the clutch pedal is depressed. Ashere illustrated, the make and break device [8 comprises a rotarycontact 19 connected by a lead 2| to one side of the resistance 11, anda fixed brush member 22 connected by a lead 23 to the other side of saidresistance. The rotary contact I9 is normally out of engagement with thebrush 22 but is moved into engagement therewith when the clutch pedal isdepressed, by suitable means such as an arm 20 connected by a link 24 tothe clutch pedal 2.

In the operation of this embodiment of the invention, and starting withthe parts in the positions illustrated, closure of the ignition switch Hcauses battery current to fiow through the control circuit and energizesthe solenoid I3 to a holding value, but since this current traverses theresistance 11, the solenoid I3 is not sufficiently energized to closethe starting switch. At the same time battery current flows through thelead IE to the field winding 15 of the generator and energizes saidfield winding by virtue of the full battery voltage applied thereto. Toeffect the starting operation, the operator is then called upon merelyto depress the clutch pedal 2 in the usual manner prior to engaging thetransmission gears. This moves the rotary contact [9 into engagementwith the brush 22 whereby the resistance l! is bridged out and thesolenoid E3 is fully energized, causing closure of the starting switchand initiation of the cranking operation. Release of the clutch pedal 2does not interrupt the cranking operation since, as above pointed out,sufficient current traverses the control circuit including theresistance IT to hold the starting switch closed whereby crankingcontinues irrespective of the position of the clutch pedal. When theengine starts, the voltage developed by the generator G risessufficiently to cause deenergization of the solenoid I3 whereupon thestarting switch opens, and is thereafter prevented from closing as longas the engine is self-operative.

The opening and closing voltages of the starting switch may be adjustedin any suitable way if desired. As here shown, the closing voltage isregulated by adjusting the compression of a spring 25 which holds theswitch open; while the opening voltage is similarly regulated byadjusting the compression of a loading spring 26 which is compressed bythe final movement of the switch plunger after closure of the switchcontacts.

It will be readily appreciated that one important advantage in the useof the resistance II to maintain the energization of the starting systemirrespective of the position of the clutch pedal is that it permits theoperator to move the car by the starting mechanism when so desired. Thisis sometimes very important as, for instance, when an engine stallswhile the car is in a position of danger, and is of course impossiblewith the conventional type of clutch pedal controlled starting device.

It will be understood that when this embodiment of the invention is usedin installations embodying an automatic clutch control, the make andbreak device [8 may be connected either to the automatically operatedclutch controlling element or to the clutch pedal only. The latterarrangement is shown in Fig. l in which the clutch operating lever 21 isarranged to be moved either by an automatic clutch control element 30 orby the pedal 2, and the link 24 is connected directly to said pedal.This arrangement has the advantage that in case of generator failure,the starter will not be actuated when the clutch is thrown outautomatically, but only when the operator depresses the clutch pedal 2.

The novel and improved results flowing from the excitation of the fieldwinding l5 directly from the battery through the ignition switch Il maybest be appreciated by reference to Fig. 4 of the drawings which showsgraphically the results secured by such separate field excitation ascompared with the normal generator output. In this figure the curve Iashows the terminal voltage of the generator with the field excited inthe normal manner during the acceleration of the generator. Curve lbshows the same during the deceleration of the generator, the differencesbetween curves la and lb being due to the usual effect of hysteresis.Curve 2a shows the field current of the generator when the field isexcited in the normal manner, during acceleration of the generator, andcurve 21) for the corresponding curve during deceleration of thegenerator. Curve 3 shows the generated voltage when the field is exciteddirectly from the battery through the ignition switch, and curve 4 showsthe corresponding field current.

It will be apparent from a study of these curves that the voltageavailable from the generator at low speeds when separately excited isuniform and free from the effect of hysteresis, and much higher thanwith a conventional generator, and the variation in such voltageresponsive to the changes in such low engine speeds is also muchgreater. As a matter of fact, the voltage generated has been found to besubstantially in direct proportion to the engine speed irrespective ofwhether the generator is being accelerated or decelerated, andirrespective of temperature changes of the generator, etc. When it isconsidered that the controlling function of the generator preferablytakes place on that portion of the curve below 300 R. P. M., it will bereadily appreciated that the vastly increased range of voltage madeavailable by separate excitation of the generator field permits muchsuperior regulation of the starting operation without necessitatingcritical adjustments of the controlling elements.

Taking for instance a typical installation in which cranking speed is200 R. P. M., the speed at which it is desired to interrupt cranking is300 R. P. M., and the speed down to which recranking is to be preventedis 50 R. P. M. The voltages of a conventional generator correspondingthereto, taken from curve la, are 0.24 volt, 0.4 volt and 0. volt. Theeffective voltages impressed on the relay coil I3 by a 6-volt batteryare then 5.76 volts, 5.6 volts, and 5.9 volts. It is necessary,therefore, to design a relay which will hold closed when the appliedvoltage is 5.76 volts, which will open when the applied voltage falls to5.6 volts, and which will not reclose until the applied voltage rises to5.9 volts.

In contrast to this, the corresponding generator voltages with agenerator in which the field is excited from the battery according tothe present invention are (curve 3) 2% volts, 3% volts and 1 volt, sothat it is merely necessary to use a relay which will hold closed at 3%effective voltage, and open at 2%; volts and will not reclose until theeffective voltage rises to 5. This obviously gives far greater latitudefor variations in the characteristics of the component parts.

Referring now to the embodiment of the invention illustrated in Fig. 2,the starting circuit and the control circuit are similar to those shownin Fig. 1, the elements being similarly numbered. In this embodiment ofthe invention, however, a make and break device 28 is arranged to beoperated by a manual control member in the form of an accelerator pedal29 for the engine as by means of a link 3| and an arm 32. The make andbreak device 28 is arranged preferably though not necessarily as shownto break the control circuit when the accelerator pedal 29 is completelyreleased. For this purpose, the lead I2 is connected to a brush 33, andthe make and break device is provided with a rotary electrode 34normally out of engagement therewith, which electrode is connected by alead |2a to the solenoid [3. The brush 33 is arranged to engage thiselectrode 34 upon initial depression of the accelerator pedal 29, and asecond brush 35 is arranged to be engaged by said electrode upon furtherdepression of the accelerator pedal, the brush 35 being adapted tobridge the resistance I by virtue of a lead 36 connected thereto.

In the operation of this embodiment of the invention, starting with theparts in their idle positions as illustrated, closure of the ignitionswitch I energizes the field 15 of the generator. Initial depression ofthe accelerator pedal -29 closes the control circuit through theresistance l1, energizing theso'lenoid 13 to a holding value. Furtherdepression of theacce'lerator *pedailcauses electrode 34 to engage thebrush 35, thus shorting out the resistance 11 and causing fullenergization of solenoid l 3 to close the-starting switch 6. Cranking ofthe engine thereupon takes place and is continued irrespective ofmovement of the accelerator pedal 29 until the engine starts, unless theaccelerator is completely released. In case of a false start of theengine of ,just willcient force to demes'h the starter pinion withoutaccelerating the generator sufiiciently to open the starting switch, itis merely necessary for the operator to release the accelerator pedalwhereupon the starter is deenergized and the starting operationmay't'hen be repeated as above set forth.

It will be appreciatedjhowever, that the greatly increased efliciency ofthe generator control according to the present invention reducespractically to the vanishing point the problem of preventing motor spinincase-of false starts, since an engine explosion which is powerfulenough to demesh the pinion is practically sure toenergize the generatorsufficiently to open the starting switch so that .the cranking operation.is automatically repeated.

The embodiment of the invention illustratedin Fig. 3 is similar to that.shown in Fig. v1, except that the make and break device 38 .is normallyclosed, and is automatically opened in response to intake vacuum whereby.a fully automatic starter control is provided. As here shown, this makeand break .device comprises a fixed contact 39 anda movable contact 4|mounted .on a flexible diaphragm 42 forming one wall of a chamber 43suitably connected .to the intake manifold 44 of the engine. Contact 39is connected by a lead 45 to one side of the resistance l1, whilecontact 4| is connected by a lead 46 to the opposite .side of saidresistance. Contacts 39 and 4| .are normally in engagement asshown butcontact 4| is adapted to be withdrawn .by intake vacuum oflow value.

In the operation of this embodiment of the invention, closure of theignition switch .|l causes energization of the generator field winding.|.5 from the battery, and also causes .closure of the starting switch 6since the resistance I1 is shorted out by contacts 39, 4|. As soon ascranking starts, the vacuum in the intake manifold 44 causes contacts39, 4| to open, but cranking continues by reason of the holding currentfor the starting switch which traverses the resistance l1. When theengine starts, the generator G causes deenergization of the solenoid |3whereby the starting switch opens and remains open until contacts 39 and4| close by failure of intake vacuum at the same time that the output ofgenerator G falls below the predetermined minimum lock-out value. Whenthese conditions are brought about by engine stall, the engine will beautomatically restarted.

In order to prevent an immediate restart in case of engine stall, whichmight cause engagement of the starting pinion during a back-rock of theengine, a time delay is preferably incorporated in the control. As hereillustrated, this time delay is obtained by means of a disc 41 suitablyfixed in the bottom of the chamber 43 and provided with a small aperture48 communicating with the intake manifold connection. It will be readilyappreciated that the reclosure of contacts 3'9, 4| will be delayed forthe desired interval after an engine stall, by suitably proportioningthe chamber 43 and selecting a disc 41' having the proper sized aperturefor the particular class of installation.

It has been iound in certain installations made according to the presentinvention that when the lead 16 from the separately excited field i5 isdirectly connected to lead I2 of the control circuit as-shown in Figs. 1and 2, when the ignition switch is opened to stop the engine, thebreaking of the battery connection to said field may cause an inductivesurge through the held in a reverse direction to the magnetizingcurrent. This inductive surge may be of sufficient voltage to traversethe control circuit including the resistance l! and "actuate thesolenoid l3 to close the starting switch. Thisca-uses a momentaryactuation-of the starting motor which is sometimes sufficient tocausethe starter gear to attempt to engage the flywheel of the engine whichcauses an undesirable click as the starter pinion strikes the flywheeland might in time cause unnecessary wearof the parts.

In order to prevent this effect, the switch. may preferably he formed asshown in Fig. 3 as a two-pole switch, the field lead 16 being connecteto one pole 5'1 and the control circuit lead l2 being connected to theother pole 52. The ignition circuit lead may obviously be connected toeither of these poles. The switch I then constitutes means forseparately simultaneously connecting the control circuit and the fieldwinding to the battery and for disconnecting the field winding from thecontrol circuit when the field winding is disconnected from the battery.Obviously this arrangement prevents the induced voltage of the fieldwinding from affecting the control circuit.

Although certain embodiments of the invention have been shown anddescribed in detail, it will be understood that other embodiments arepossible and that changes may be made in the ar rangement of the partswithout departing from thespiriit 0f the invention as defined in theclaims appended Ihereto.

What is claimed is:

1. A power plant including an internal combustion engine, startingmechanism therefor including 'a magnetic starting switch, a controlcircuit for said starting switch including a battery, a manual switchand a make and break device; a manually operable power control member,means for operating said make and break device from said control member,a shunt resistor for maintaining the effective energization of thecontrol circuit irrespective of opening of the make and break device, anengine-driven generator having a field winding connected in shunt withthe portion of the control circuit including said make and break device,and means including said generator for maintaining said control circuitdeenergized responsive to self-operation of the engine at or above apredetermined speed, said shunt resistor being of such value as tocooperate with the voltage of the generator in opposing flow of batterycurrent through the magnetic starting switch to cause said switch toopen at a predetermined engine speed.

2. A power plant including an internal combustion engine and a manuallyoperable power control member, starting mechanism for said engineincluding a magnetic starting switch, a control circuit for saidstarting switch including a make and break device, connecting meanswhereby operation of the control member actuates said make and breakdevice, a shunt resistor for maintaining the effective energization ofthe control circuit irrespective of the opening of the make and breakdevice, an engine-driven generator having an armature and a fieldwinding, connections whereby the armature voltage of the generatoropposes energization of the starting switch, said shunt resistor beingof such value as to cooperate with the voltage of the generator inopposing flow of battery current through the mag-- netic starting switchto cause said switch to open at a predetermined engine speed, andmanually operable means for simultaneously controlling the energizationof the control circuit and of said field winding.

3. A power plant including an internal combustion engine and a manuallyoperable power control member, starting mechanism for said engineincluding a magnetic starting switch, a con trol circuit for saidstarting switch including a battery and a make and break device,connecting means whereby operation of the control member actuates saidmake and break device to cause closure of the starting switch, means forholding the starting switch closed, irrespective of opening said makeand break device, an engine driven generator having an armature and afield winding, connections whereby the generator opposes the fiow ofbattery current through the con trol circuit, and manually operablemeans for simultaneously completing the control circuit and connectingsaid field winding directly to the battery.

4. A power plant including an internal combustion engine and a manuallyoperable power control member, starting mechanism for said engineincluding a magnetic starting switch, a control circuit for saidstarting switch including a make and break device, connecting meanswhereby operation of the control member actuates said make and breakdevice, a connection bridging said make and break device having suchresistance as to reduce the flow of current in the control circuit to aholding value for the magnetic starting switch, an engine-drivengenerator having an armature and a field winding, means including saidgenerator for opposing energization of the starting switch duringself-operation of the engine, and a manually operable switch forsimultaneously completing the control circuit and connecting said fieldwinding directly to the battery.

5. A power plant including an internal combustion engine, startingmechanism therefor including a magnetic starting switch having anoperating solenoid, a control circuit for said starting switch includinga battery, a manual switch, a make and break device and said solenoid;means for operating said make and break device, a shunt resistor formaintaining the efiective energization of the control circuitirrespective of opening of the make and break device, an engine-drivengenerator having a field winding so connected that when the controlcircuit is energized, said field winding is in shunt with the portion ofthe control circuit including said make and break device and saidsolenoid, and means including said generator for maintaining saidcontrol circuit deenergized responsive to self-operation of the engineat or above a predetermined speed, said shunt resistor being of suchvalue as to cooperate with the voltage of the generator in opposing flowof battery current through the magnetic starting switch to cause saidswitch to open at a predetermined engine speed.

6. In combination with an internal combustion engine, starting mechanismtherefor including a battery and a magnetic starting switch, a controlcircuit for said starting switch including said battery, a manualswitch, and a make and break device, opening means for the make andbreak device responsive to self-operation of the engine, means in shuntwith said opening means for holding the starting switch closedirrespective of opening of the make and break device, an engine-drivengenerator having a field winding, and means including said generator fordeenergizing said control circuit and maintaining it inoperative duringrotaton of the engine above a predetermined speed, said field windingbeing connected directly to said battery through said manual switch.

7. In combination with an internal combustion engine, starting mechanismtherefor including a magnetic starting switch, a control circuit forsaid starting switch including a battery, a manual switch and a normallyclosed make and break device, means responsive to intake vacuum foropening said make and break device, means for passing current of aholding value for said magnetic switch around said make and breakdevice, and an engine-driven generator having an armature and a fieldwinding, said armature being in circuit with the magnetic switch andmake and break device, and said field Winding being in shunt with theportion of the control circuit which includes the make and break deviceand the magnetic switch.

PAUL H. MAURER.

